Effects of Electrodes on the Electric Properties of Pb(Zr,Ti)O3 Films Deposited by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition

The effects of electrodes on the deposition characteristics and electrical properties of lead zirconate titanate (PZT) films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) were investigated. Pt/Ti/SiO2/Si and RuO2/SiO2/Si were used as bottom electrodes (substrates) for PZT capacitors. Pt and RuO2 were used as top electrodes. The nucleation of the perovskite phase was more difficult on RuO2 substrates than on Pt/Ti substrates, and the PZT films grown on RuO2 substrates tend to have Pb-based second phases. Precise control of the flow rates of metalorganic sources (particularly the lead source) and the introduction of a proper seed layer are required to obtain films of the single perovskite phase and good electrical properties on the RuO2 substrate. An excellent leakage current density of 10-6 A/cm2 at 150 kV/cm was obtained from the Pt(top)/PZT/RuO2(bottom) capacitor with the introduction of a 4 nm-thick Ti-oxide seed layer. The polarization fatigue and current leakage characteristics of the PZT capacitors with four different electrode configurations (Pt ∥Pt, RuO2 ∥Pt, Pt ∥RuO2, and RuO2 ∥RuO2) were also investigated. Only the RuO2/PZT/RuO2 capacitor did not show any polarization fatigue even after 1010 cycles, while the other capacitors, whose either top or bottom electrode was Pt, showed distinct polarization fatigues. The RuO2/PZT/RuO2 capacitor, however, showed a leakage current density of as high as 10-4 A/cm2 at 100 kV/cm.